This invention relates to paper sheet accumulators, and more specifically to a paper sheet accumulator wherein paper sheets are accumulated individually and then dispensed collectively as a stack.
Numerous accumulators have been used for accumulating paper sheets and documents into stacks and then transporting the accumulated stacks. For instance, Driscoll et al. (U.S. Pat. No. 5,147,092) discloses a flat accumulator comprised of upper and lower sets of driven elastic belts.
Although a flat type of accumulator is appropriate for some applications, its dimensions are too large or bulky for other applications. This related art cannot conform to the space limitations and layout of certain machines in which a sheet accumulator must form a component part. In addition to problems of size and shape, the related art also has problems when accumulating paper that does not have normal buckling properties, such as perforated paper. For example, Miller, (U.S. Pat. No. 5,356,263) discloses a sheet accumulator in which it is necessary for sheets of paper to buckle very substantially, which becomes problematic when the sheet of paper has characteristics inconsistent with normal buckling (e.g. perforated paper). Another problem encountered with some of the related art is that the accumulation process may yield sheets that are out of order or inverted; in other words, the stack of paper produced may be either face down or lead-edge trailing relative to the input sheets of paper.
The main objective of this invention is to provide a sheet accumulator for accumulating sheets of paper one by one which arrive at the sheet accumulator along a main linear paper path, and for then allowing the stack of accumulated sheets to exit the accumulator. Another objective of the present invention is to minimize the amount of space required by the sheet accumulator. Accordingly, the present invention is a compactly designed sheet accumulator in which the paper path is circular. This design conforms to space limitations which other sheet accumulators, such as flat accumulators, are unable to achieve.
According to the present invention, individual sheets of paper moving along a main path enter into the accumulator one at a time, whereupon each sheet registers its lead edge against a backstop. Then a set of gripper jaws seizes the lead edge of that sheet of paper, while also seizing the lead edges of any other sheets of paper that are already registered against the backstop, whereupon the jaws pull all of the gripped sheets of paper along a circular path until the gripper jaws return to a home location. At the home location, the jaws open so as to accept an additional sheet of paper. The process repeats itself until a predetermined number of sheets are accumulated into a complete stack. Once this complete stack of sheets is registered against the backstop, the stack is exited out of the sheet accumulator into the main linear paper path.
The present invention is designed to offer an economical sheet accumulator with a compact configuration that allows the accumulator to fit into spaces where many other sheet accumulators cannot fit. The present invention is also designed in such a way as to easily handle paper prone to buckling, such as perforated paper.